Summary

This was for my cheap 90s taps, a push fit diffuser. This is for a 15mm hole, there is a larger lip to stop it going too far in. of 16.8mm (which is why your slicer will show a 16.8mm dia not 15mm)

Print 100% fill it'll take about 15 minutes for 2 of them.

This is really to stop the tap dribbling down its own spout. Made in tinker cad, 30 minutes, first time ever using it, no training so surprised at how fast this was done.

fits both of my taps perfectly.